In the years following the Civil War, more than 150 Union and Confederate veterans served as United States senators, helping to chart the nation’s course well into the 20th century.

The last Union veteran, and the last Civil War veteran, to serve in the United States Senate was Francis E. Warren of Wyoming. Warren earned the Congressional Medal of Honor for disabling a Confederate artillery as a young soldier at the 1863 Seige of Port Hudson, La. In 1890 he became one of Wyoming’s first two senators. Warren is credited as being the first senator to hire a woman to a professional Senate staff position, as well as the first senator to hire an African American to the Senate’s professional staff. He was the Senate’s longest-serving member when he died in office in 1929, at age 85.

Charles S. Thomas of Colorado was the last Confederate veteran to serve in the Senate. Born in Georgia, he served briefly as a teenager in the Confederate Army. He settled in Denver after the war, where he built a law practice and pursued a Senate career. Following three failed attempts to gain a Senate seat, the 63-year-old Thomas finally became a U.S. senator in 1913, a position he held until 1921. During his years in the Senate, Thomas became known for a rather unconventional habit that marked the arrival of springtime in the Senate Chamber.